It was a two-day meeting, described as a private, get-acquainted workshop. The idea was to bring together for the first time 36 scientists from around the world working on genomic techniques to revive extinct species, along with related projects. Molecular biology would meet conservation biology.

Toward the end of the second day, Stanley Temple, one of the founders of conservation biology, was asked to draft a list of “points we agree on“ to reflect what the group had learned from 29 ten-minute presentations and a good deal of discussion. After further discussion, most of the group agreed with most of the following points for helping de-extinction proceed responsibly:

De-extinction is exciting, moving forward, and will eventually be tried.

It’s unlikely to happen very soon; we have time to do it right.

Research on the enabling technologies should be encouraged, coordinated, and funded.

Mutually beneficial linkages with other on-going endeavors (e.g., endangered species recovery, ecosystem restoration, and ex situ bio-banks) should be built.

Priority-setting for targets and outcomes is essential “before the train leaves the station” and our discussions here have advanced the thought process.

De-extinction is certain to be controversial for some.

To deal with anticipated obstacles there should be a pro-active lead-up to the day when de-extinction is attempted (i.e., building trust and knowledge):

To open the first day, Terry Garcia, head of Missions at National Geographic, remarked that his organization expects this century to be the greatest period of exploration ever. “We are now able to open doors that seemed to be permanently closed to us in the past. In many cases the key to those doors is new technology.” On one of the most forbidding of the doors is written: “Extinction is forever.”

Successes with cloning

To begin the first session, Alberto Fernández-Ariasreported on a 2003 effort to clone an extinct subspecies of Spanish ibex, called the bucardo or Pyrenean ibex. In 1999 the last bucardo, a female named Celia, was captured from the wild in Ordesa and Monte Perdido National Park, some tissue from her ear was cryopreserved in liquid nitrogen, and she was returned to the wild. In 2000 she was found dead under a fallen tree. Bucardos were extinct.

In 2003 a team led by Dr. José Folch attempted to clone Celia, transferring her DNA into enucleated eggs from domestic goats, then implanting the 3-to-6-cell embryos in surrogate mother goats. The most successful pregnancies were in hybrids developed from a cross between Spanish ibex and domestic goats. One pregnancy went all the way to term, and a baby bucardo was delivered by caesarean section. Genetic analysis showed it was a living member of the formerly extinct species.

Unfortunately the baby bucardo lived for only ten minutes, succumbing to a malformed lung—respiration failure is a common problem in cloning experiments. Interspecies cloning has come a long way since 2003. Dr. Fernández-Arias expects new attempts will be made in the next few years to revive the bucardo and eventually return a sustainable population to the wild.

The Frozen Zoo, a project within the San Diego Zoo that has been running for 35 years, has cryopreserved samples (sperm, eggs, embryos, skin, etc.) from 10,000 individual animals in 1,000 vertebrate species. Oliver Rydersaid that samples from the Frozen Zoo have been used for hundreds of studies, and two endangered species have been cloned from the collection—the gaur and a banteng (by Robert Lanza).

The Frozen Zoo is playing a crucial role in a major new initiative called “Genome 10K,” which aims to catalog full genome data for 10,000 vertebrate species—approximately one for every genus. With scientists and curators from institutions all over the world participating, Ryder expects this “ambitious and inspiring” project to enable reading the genetic heritage of all species. A hundred species have already been sequenced.

Now that fibroblast cell cultures from skin can be used to make induced pluripotent stem cells, Ryder concluded, samples from the Frozen Zoo have been used to aid in the conservation of highly endangered species. With germ cells derived from the pluripotent stem cells, genetic variability and reproductive vigor could be restored to severely reduced species such as the northern white rhino and a primate called the drill.

Robert Lanzafocussed on the new techniques that move beyond nuclear transfer to the use of cellular reprogramming to make induced pluripotent stem cells. Difficulties in working between species can be reduced when the living genome is as close as possible to the extinct genome.

Thirteen years ago Lanza found that the genome of the domestic cow was close enough to the endangered gaur (also called “Indian bison“) that nuclear transfer could create gaur embryos in cow surrogate mothers, though the embryos had the mitochondrial cow DNA that came along with material in the enucleated cow eggs. A beautiful baby gaur resulted, but it died after two days of ordinary dysentery. Later, working with 25-year-old Frozen Zoo tissue from the endangered Javan banteng, the team again used cow eggs and this time got a healthy baby banteng that survived and prospered.

As for extinct species, Lanza declared there is no hope of reviving dinosaurs because “You can’t clone from stone.” But there is hope with species where there is recoverable DNA. Just this year it has become possible with induced pluripotent stem cells to generate primordial germ cells that yield viable sperm and eggs that in turn yield viable progeny. “This is the way we will probably go forward.”

Some projects underway

The aurochs once dominated Europe and northern Asia the way the American bison dominated North America, said Henri Kerkdijk-Otten. It was a huge ox, up to six feet high (1.85 meters) at the shoulder, extinct since 1627. As a megaherbivore it played a key role in maintaining Europe’s ancient mix of forest and grasslands.

The species is being reconstructed by selective back-breeding of seven different hardy, primitive-looking cattle breeds that still live in Europe. Most of the work so far has focussed on selecting for the known phenotypic traits of the aurochs—size, color, hardiness, etc.. Genotype elements are being added as genetic information on the aurochs becomes available. The match does not have to be perfect to be “fit for purpose.” Kerkdijk-Otten noted that as rewilding proceeds and the nature reserve size goes from small to medium to large, the ethical dimension goes from “animal ethics” to “respect for potential wildness” to “eco-ethics.” The gradient is from animal welfare at one end to ecosystem health at the other.

The project is run by the Tauros Foundation in the Netherlands, with the collaboration of 14 nations and working closely with Rewilding Europe and European Wildlife. The Megafauna Foundation plans similar programs for wild horses, the European water buffalo, and the Asiatic wild ass.

The most recent effort to clone the woolly mammoth by finding tissue with still-viable cells in the frozen tundra is a joint Russian/South Korean project. Insung Hwanggave a report on early results from the group’s first expedition in Siberia but preferred to keep it off the record. No viable mammoth cells have been confirmed as yet.

Also off the record were early results from an Australian endeavor called Project Lazarus, which intends to revive a particularly exotic extinct species. Michael Archerand David Frenchdescribed the goals and techniques, mainly refinements of somatic cell nuclear transfer. Results to date have resulted in successful recovery of nuclei of the extinct species, introduction of these nuclei into the enucleated eggs of a living distant relative, fusion of the donor nucleus and host egg, and consequent development of embryos that have already progressed to the blastulae stage. DNA testing of the cells of these embryos indicates that they contain the DNA of the extinct species

One reason for the low profile of Project Lazarus, Michael Archerexplained, was his experience in being constantly pressured by the media in relation to a previous project he started in 2000 that was aimed at recovering and characterizing the DNA of the extinct thylacine (also known as the Tasmanian Wolf) from museum specimens, with the long-term goal, when technology caught up, of bringing back a live thylacine. While the DNA goals were all successful, the Project did not proceed after Archer’s term at the Australian Museum was up in 2003. It was at this time that he initiated the Lazarus Project, but deliberately without media involvement.

If the thylacine can be brought back eventually, the Tasmanian wilderness is still suitable habitat, and the thylacine could resume its ecological role, perhaps even reducing the infectious cancer problem in Tasmanian devils since direct competition would spread them out.

One remarkable success with the thylacine genome was reported by Marilyn Renfree. The team she worked with got a non-coding gene from the extinct animal to express in a mouse fetus. A regulatory gene for cartilage formation (Col2a1) from thylacine DNA was injected into mouse zygotes and there performed the same function it did in the extinct animal.

One of the most moving images of the workshop was historic film footage Renfree showed of thylacines pacing and jumping in their Hobart zoo pen—the last one died in 1936. The animals were so full of wolfish life! David Burney commented that the emotion we felt was just a tiny sample of what people will experience when they see a living mammoth.

Emerging genomic techniques

George Churchbegan by noting that since 2005, biotech capability (sequencing, DNA synthesis and assembly, and placement into stem cells) has been accelerating much faster than Moore’s Law. Costs are coming down every year by a factor of 6X to 11X. (Moore’s Law is 1.5X.) Church expects that within five years we will be able to make a dozen edits to a 3-billion-base-pair genome (size of many mammal and bird genomes) for $30,000 and synthesize 100 kbp (1,000 base pair) blocks for less than $10,000 each.

Church’s lab at the Wyss Institute has a machine and protocol called MAGE—Multiplex Automated Genome Engineering—which allows DNA-directed or RNA-directed precise homologous recombination of multiple genes simultaneously. You can test what you get in cells or organs-on-a-chip before trying them on a complete organism. With the use of zinc finger nucleases, you can replace a gene in a living species with the equivalent gene from an extinct species precisely—right down to the individual base pair level.

Revive & Restore’s effort to bring back the passenger pigeon is being led by Ben Novak. Ancient DNA from museum specimens of passenger pigeons has been sequenced by Novak, Beth Shapiro, and others. Novak found that a pinhead-size piece of tissue such as a toe pad was all that was needed. It helps to sequence the genome of the closest living relative, in this case the band-tailed pigeon, to use as a reference sequence for getting better assembly. Novak‘s initial work on the band-tailed genome showed it to be 10 percent closer to the passenger pigeon than the rock pigeon. The hope is that George Church’s technique may be used to effectively transform the band-tailed pigeon into a passenger pigeon, stage by stage. Novak is confident it will eventually become possible to resurrect an extinct species even when all you have is tissue from a single specimen such as the dodo (another extinct pigeon). To head off inbreeding problems you may be able to borrow allelic variations from closely related living species.

According to Michael McGrew, birds are particularly manageable for working with primordial germ cells, because the germ cell lineage is separated early from somatic cells. His colleagues in Dubai got chicken germ cells to generate chicken sperm in a male duck! That chimeric duck mated with a chicken to produce normal chicken young, which were fertile. The same technique could be used with, say, germ cells induced from cryopreserved skin cells (fibroblasts) of an endangered falcon to produce pure falcon chicks from chicken parents. The process might work for reconstituted passenger pigeon germ cells as well. The use of chickens as a xenogenic host could also be a technique for avian preservation.

Noting that accuracy in DNA synthesis is both difficult and essential, Jean-Marie Rouillardsaid that his lab at MYcroarray gets around the problem with sorted libraries of error-free oligonucleotides. Some initial work suggests that assembling a 4 billion base pair mammoth genome might cost $125 million. Important problems that would have to be solved along the way include accurate chromosome assembly, epigenetics, heterozygosity, genome compatibility, and xenopregnancies. Solving those problems would help advance synthetic biology, including tools for gene therapy and enhancing biodiversity.

The world leader in DNA sequencing is Beijing Genomics Institute (BGI). Only started in 1999, Guojie Zhangnoted, BGI’s multiple centers now process the equivalent of 3,000 human genomes a day. The institute has two major programs—one is human health; the other, called Tree of Life, is sequencing plant, animal, and microbial genomes. Working with Genome 10K, they have sequenced 120 vertebrates and are taking on 100 more. Another 207 species are planned to cover the full range of biota from primates to nematodes. Their work on ancient DNA has included analysis of a 4,000-year-old Eskimo that revealed he was balding, with brown eyes, type A blood, and dry ear wax. BGI is interested in working with efforts to study and revive extinct species.

Interpreting extinct molecules

DNA is a fragile molecule, said Tom Gilbert, easily damaged by heat, water, oxygen, and radiation. The recent study of DNA in bones of the extinct moa suggests a half-life of 521 years. Ancient DNA samples typically have large quantities of contaminant DNA, some miscoding lesions, and an abundance of small fragments yielding reads that are too short for assembly—especially in regions of repetitive sequences. (“Introns are harder than codons.”)

No DNA has yet been recovered from dinosaur fossils, but Mary Schweitzershowed evidence she has found ancient dinosaur proteins preserved in the remnants of osteocytes—bone cells—in their fossilized bones.

As an alternative to PCR techniques, said Michi Hofreiter, hybridization capture offers a low-cost, high-throughput, contamination-tolerant way to target specific ancient DNA regions affecting physiological function. It is a shortcut to “functional paleogenetics,” yielding insights such as the degree to which mammoths had cold-adapted blood circulation. It can be applied efficiently to multiple specimens and can even span species that are not closely related.

Studying mammoth ancient DNA, Hendrik Poinarexplained, reveals that they were not all hairy, they varied regionally, and they hybridized during their declining millennia. They were forest dwellers, about the size of modern elephants, a closer cousin to Asian elephants than the African. Like modern elephants they probably educated their young. The last of them died out just 3,000 years ago, on Wrangel Island in the Arctic north of Siberia. To revive the mammoths will require developing abilities we don’t yet have to assemble and manipulate large chromosomes and to manage issues of epigentics and heterozygosity.

Reviving extinct ecosystems

Vast Arctic grasslands called the mammoth steppe, said Sergey Zimov, once comprised the world’s largest biome, maintained by millions of herbivores with a density similar to the African savanna. He theorizes that the Pleistocene decline of megafauna in the north—caused mostly by human impacts—led to the steppe being replaced by tundra and boreal forest. Global warming is now being exacerbated by the thawing tundra permafrost releasing greenhouse gases.

Zimov set about showing how the steppe grazing system and the steppe itself could be restored by creating a 62-square-mile “Pleistocene Park“ in northern Siberia, where a diverse array of herbivores (and some predators) could be fenced to establish the density that used to exist on the steppe. He began in 1988 with wild Yakutian horses, adding wild musk oxes, reindeer, and bison. Their grazing and trampling has succeeded in turning moss-choked tundra into ecologically rich grassland which is collecting carbon rather than releasing it.

Zimov told the de-extinction workshop he would gladly populate Pleistocene Park with revived cave bears, cave hyenas, a grass-eating reindeer, some woolly rhinoceros, and of course the woolly mammoth. “To fight the forest, instead of mammoths we now use military tanks. Unfortunately they don’t create dung.”

Frans Veraalso emphasized the role of wild grazing animals in relation to the Oostvaardersplassen, a 23-square-mile nature reserve in the Netherlands which is recreating a version of the ancient European landscape. People wrongly assume that when abandoned farmland converts to closed-canopy forest, “nature” has been restored. A dense population of wild herbivores made Europe a far more biodiverse mix of grasslands and forest. The original aurochs and tarpan horses are gone, but they can be replaced by functional equivalents such as Heck cattle and Konik horses. As a result, the Oostvaardersplassen has attracted a full suite of endangered species, including graylag geese, bearded reedlings, and white-tailed eagles.

Huge ethical issues emerge around how animals die in a public nature reserve. In nature, carrying capacity is not determined by predators so much as by starvation. It comes down to who survives the winter. The public would not accept watching animals starve. So the managers of the reserve shoot the clearly failing animals early in the winter. The way that is made acceptable is to have a veterinarian on hand when the animals are culled.

The use of ecological functional equivalents came up again in David Burney’s presentation on Hawaii’s Makauwahi Cave Reserve on the island of Kauai. A sinkhole at the site yielded paleoecology data covering the past 10,000 years. Clearly missing from the current bird fauna are mesoherbivores such as an extinct “tortoise-billed” flightless duck that specialized in eating plants close to the ground. One consequence of their absence is the way alien invasive plants carpet the Hawaiian islands.

Hundreds of volunteers replanted the reserve with 6,000 native plants of 100 species, but they could not keep up with the relentless regrowth of the alien invasive plants. Burney took a cue from a reserve on Rodrigues Island where introduced land tortoises (alien but obligingly noninvasive) grazed the invasive plants aggressively and left the native plants alone. Land tortoises never reached the Hawaiian Islands; that’s why “tortoise-billed” birds evolved there. To serve as an “ecological surrogate,” African giant tortoises (Sulcata) that are widely kept as pets were brought in and tested at Makauwahi. They have proved to be brilliant weed-eaters, helping restore a living portion of ancient Kauai.

Burney made the additional point that once you have good paleoecological data, you don’t have to feel limited to restoring endangered (or de-extincted) species in situ (where they were last seen living) or ex situ (in zoos). You might introduce them in a wider range of places that are “inter-situ” (where they used to live long ago).

America’s great eastern deciduous forest lost a quarter of its trees and a crucial keystone species when the billions of fully-grown American chestnut trees succumbed to an invasive fungus between 1909 and 1950. William Powellexplained that the huge annual mast production of palatable nuts fed countless animals (including extinct passenger pigeons and Carolina parakeets) as well as humans. Not formally extinct, the trees live on at the root, but their shoots cannot mature. So great was the sense of loss that since 1983 The American Chestnut Foundation has been running an ambitious program to cross the American chestnut with the blight-resistant Chinese chestnut. Now in their fourth generation of selective back-crossing, the trees are 15/16 American chestnut, are pretty resistant to the blight, and are being released gradually to repopulate the forest.

Powell, working with Chuck Maynard, took a more biotech approach, starting in 1990. They observed that the blight cankers do their damage with oxalic acid. There is a gene in wheat that detoxifies oxalic acid. When that gene was engineered into the American chestnut, blight resistance resulted. Their transgenic trees are being incorporated into the American chestnut revival. Powell noted that the back-crossed American Chestnut has about 45,000 genes, some 2,800 (1/16th) of them from the Chinese tree. His transgenic American chestnut has only three to six genes that are new to the tree, and they are introduced with more precision.

Conservation perspectives

The second day began with a panel of conservation professionals, moderated by National Geographic’s John Francis. Joel Bergerhad a cautionary tale to report, based on his experience in 2006 with eleven other scientists who proposed a “Pleistocene rewilding” project for North America. The idea was to restore ecosystems by replacing extinct keystone species with modern ecological surrogates—elephants for mammoths, Przewalski’s horse for the tarpan, African cheetahs for the old New World cheetahs. The project would go slowly over decades, starting with small species.

Nature magazine put out a press release about lions and elephants in Kansas. An instant media frenzy led to headlines like “Who Wants a Pleistocene-Era Backyard?” Berger admitted, “We blew it in terms of media communications.” Controversy meant questions about credibility, and the project went quiet. Rewilding has begun nevertheless. Black-footed ferrets have been reintroduced; so has the Bolton tortoise; California condors; wolves; musk oxes in Alaska. Berger concluded, “Are we thinking about species per se, or are we thinking about ecologically functional relationships using keystones?”

Kate Jonessaid that early discussion with her colleagues at IUCN showed there is concern about funding being diverted from protecting endangered species to expensive efforts to revive extinct ones. She herself has been converted to enthusiasm for de-extinction, she’s impressed by the technology, and she suggests that priorities carefully developed for selecting endangered species most worth protecting might also apply to selecting extinct species most worth bringing back. Criteria could include keystone qualities, ecological services provided, available habitat, and future climate impacts. (The website at edgeofexistence.org spells out the criteria. The acronym EDGE means “Evolutionarily Distinct and Globally Endangered.”)

Peter Kareivanoted that one of the threads in conservation is “awe and wonder,” and de-extinction can fit perfectly in that. The question to ask is: How can this play out well for conservation? De-extinction could help us shed nostalgia as a dominant theme in conservation and we could stop worrying about labels like “all natural.” As human population pressure starts to diminish in this century, there could be real opportunities for rewilding. A mosaic of nature and technology could be healthy for conservation. We need to proceed strategically—focus on iconic species and iconic ecosystems massively restored.

Stanley Templesaid, “De-extinction is essentially a game-changer for the conservation biology movement. It changes one of our principal arguments, that extinction is forever.” He added, “There is much to be gained for endangered species recovery from de-extinction technologies, especially the very rare species that have lost their genetic diversity.” Likewise, rewilding methodologies developed for endangered species can be applied directly to rewilding extinct species. Species that went extinct for a single, correctable reason will have a better chance than most if that problem can be corrected. Be aware that any reintroduction of formerly extinct species will be very closely regulated.

In the discussion that followed, Kareiva commented, “Putting together futurism with respect for species is something we have not done as a conservation community, and I see that as the only way the community is going to last and thrive.” Anticipating that rewilding revived species will be highly regulated, Temple advised familiarizing the regulators early, gradually, and thoughtfully. He recalled that getting permission to reintroduce wolves to Yellowstone Park took 20 years. Ben Novak reminded the group about the widespread cool factor with de-extinction, especially for younger people. They want the mammoth back, even if it’s in a zoo. “Remember that zoos support conservation programs. You get 10,000 extra visitors to see the mammoth, that’s a lot of money for conservation.”

De-extinction ethics

The “ethics panel,” Hank Greelypointed out, was really about the full range of issues sometimes call ELSI—Ethical, Legal, and Social Implications. Hillary Bokurged bearing in mind the welfare of the animals. Alejandro Camachosaid there are a wide range of laws affecting captive breeding and reintroducing species to the wild. These include the captive breeding regulations of the Endangered Species Act (ESA), the Toxic Substances Control Act, the National Environmental Policy Act, the Federal Insecticide, Fungicide, and Rodenticide Act, the Animal Welfare Act, and the Federal Food Drug and Cosmetic Act. A different set of laws would apply and might restrict the introduction of any revived species. These include the ESA’s regulations on experimental populations, as well as the many different laws regulating the management of federal, state, and private lands and marine areas; invasive species; vulnerable and rare species; and other wildlife. Because these laws were created without anticipation of the distinctive issues raised by de-extinction, they are likely to apply to revival and reintroduction in anachronistic ways, and thus almost certainly should be revisited.

Jacob Sherkowraised the question of patenting revived species. He thought it could be done legally, but why would you do it? You might do it defensively, to prevent others from carrying out revival irresponsibly. Nathan Wolfesuggested that endogenous retroviruses, which reside in genomes, might become an issue. “Every once in a while they pop out and become exogenous again. It’s very low probability, but high impact.“ Some recombination between a mammoth endogenous retrovirus and an elephant exogenous retrovirus could be harmful to the mammoth or to other elephants. You could anticipate the problem with careful mapping and perhaps remove questionable retroviruses from the genome of the species being revived.

Hank Greely noted that when a genetically engineered “GloFish” was introduced in the US in 2003, the Food and Drug Administration okayed it, but California’s Department of Fish and Game outlawed it in the state. The FDA usually gets involved only if the organism in question is eaten by humans.

Why do it?

George Church led a short discussion on what is most appealing about the prospect of de-extinction. Jamie Shreeve said the deep appeal is that it is a form of cheating death. “It is overcoming death’s finality. It is reversing the irreversible.“ David Burney observed that if de-extinction is technically possible, then it’s inevitable, so it might as well be embraced. “This is a new subject for us to explore. We’ll learn a ton of stuff.” Marilyn Renfree said that de-extinction can offer one more layer of backup for saving endangered species; it’s a form of fail-safe. Several people noted that de-extinction technology will provide ways to reintroduce genetic diversity to species that have dangerously small living populations. Michael Archer said that museum collections of preserved animal and plant specimens, maintained at great expense, now have a whole additional justification.

Henri Kerkdijk-Otten said, “For me it’s very simple. It’s undoing damage that we have done.” Stewart Brand drew a parallel with the first photographs of Earth from space, which replaced the mushroom cloud as the iconic image of our times. “It replaced an image of fear with an image of hope.“ Unexpectedly, the Earth photos set loose the modern environmental movement. Reviving extinct species will be hopeful news, much like the “Green List” of endangered species that are doing better being added to IUCN’s Red List publications. We can expect “unintended benefits” from de-extinction.

Whither the tech?

Discussion after lunch, led by Robert Lanza, focussed on next steps with de-extinction technology. Ryan Phelan suggested we could begin with mice, because they are such a well studied and tractable lab animal. Perhaps traits from an extinct mouse (such as Austalia’s long-tailed hopping mouse or Maclear’s rat) could be swapped into a lab mouse as proof that George Church’s homologous recombination technique can work. On the question of whether biotech capabilities will keep accelerating exponentially, Church noted that the field keeps being well funded because of its human medical applications. We could look for possible crossovers from de-extinction back into human medicine such as better ways to determine where pandemics come from, when wild-animal reservoirs are involved.

Reversing extinction vs. preventing extinction

In discussion led by Kate Jones about the relation between de-extinction and extinction-prevention (protecting endangered species), it became clear there are some areas of strong overlap. Criteria developed for selecting the endangered species most worth protecting can be applied to selecting the extinct species most worth bringing back. Likewise, protecting and restoring habitat for endangered species might become even more dramatic and fundable when formerly extinct species are added to the mix. Oliver Ryder pointed out that the northern white rhino, with only four non-mating animals still alive, is effectively extinct. But with his biobank of frozen tissues from a wider range of white rhinos, and perhaps even some alleles from the DNA of museum specimens, fertility and genetic diversity could be brought to the remaining rhinos. De-extinction techniques would help bring the severely endangered animals back to ongoing viability. Franz Vera noted, “Some endangered species remain endangered because their gene pool is too small.”

Which extinct species should have the highest priority for revival? Criteria that emerged from a brief discussion were divided into what is practical technically and what has the most interest for conservation. Current revival techniques require:

Recoverable ancient DNA or cryopreserved viable cells.

Enough specimens for genetic diversity.

A close living relative (for sequencing reference and potential homologous recombination).

Conservation prefers:

Beloved species.

Keystone species, especially for a needed ecological function or as support for currently endangered species.

Evolutionarily distinct (rather than a minor sub-species).

Manageable for captive breeding.

Suitable habitat available.

Can’t do ecological harm.

Removable if it does prove harmful.

More on restoring ecosystems

During discussion of restoring ecosystems, led by Joel Berger, William Powell observed that when you rewild a formerly extinct species, some people will worry about what it replaces, which might be some creature they know and love. When Powell’s American chestnuts take up their old role in the eastern US forest, they will transform some oak-hickory forest. People think the forests as they are now are just fine—a classic case of “shifting baseline.“ (Frans Vera commented that Europe has an even worse version of the same problem.) David Burney said that in terms of having a large predator to manage your herds of wild megaherbivores, the reality is you don’t need to revive the short-faced bear. “There are plenty of guys out there with high-powered rifles that are quite happy to occupy the short-faced bear niche. We can de-emphasize the big scary carnivores. We don’t really need them.”

Next steps

In the final discussion on public relations and next steps, Hank Greely pointed out that there will be attacks. He was involved in the Human Genome Diversity Project to sample human DNA from around the world. “It quickly got tagged as ‘the vampire project.‘ It was accused of collecting samples for the CIA so the United States could make ethnic-specific biological weapons. There was a coalition of fourteen scientists from around the world who responded effectively in a timely way.“

William Powell told how essential it was for reviving the America chestnut to have a large lay membership supporting the project. The American Chestnut Foundation has 3,000 members. They volunteer for planting work, they contact their senators, they find and hire people like him. “Whatever organism you want to bring back, you need to have a group of dedicated people supporting you.” Kate Jones mentioned the importance of getting citizen-science groups involved in helping with the research.

Ross MacPheehad some concluding remarks. As a curator at the American Museum of Natural History in New York he‘s noticed that the public is fascinated by anything that might be referred to as “mythic creatures—unicorns, dragons.” It fires their imagination. Extinct animals such as mammoths have that quality. If he had an exhibition on de-extinction, people would bring that level of fascination to contemplating preserved specimens of extinct creatures. The thought of bringing those creatures back fires the imagination. “They will feel that it is a daring thing to do and the right thing to do.”

Stewart Brand opined that it‘s appropriate to have the “Revive & Restore” project incubating within The Long Now Foundation, where the “long now” is defined as “the last 10,000 years and the next 10,000 years.” The last ten millennia is when most of the human-caused extinctions occurred, and yet DNA from those species remains readable. Undertaking to revive some of those creatures means engaging the time scale of species and habitats and continents. “It is not measured in years or decades, but at least in centuries. Reviving extinct species is a long, slow, gradual, exciting process. I love to see civilization stepping up that kind of thing.”

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(The workshop was organized by Ryan Phelan, working with Jamie Shreeve and Stewart Brand, plus steering committee members Hank Greely, Hendrik Poinar, Ross MacPhee, and George Church. Crucial assistance was provided by Lacey Gray at National Geographic and Kim Vassershteyn at Revive & Restore. The National Geographic Society hosted and funded the meeting. It cost about $74,000.)